The present invention is directed to socket warpage reduction. More particularly, the present invention is directed to socket warpage reduction apparatus and methods.
Electrical sockets may be used to secure electronic packages and/or integrated circuit (IC) devices, for example, onto a system board (e.g. a mother board or a printed circuit board xe2x80x9cPCBxe2x80x9d) of an electronic system. These electrical sockets may be constructed for easy installation and replacement of electronic packages (e.g. electrical components) and/or IC devices such as complex memory chips and advanced processor chips. The electrical sockets may also be available in different sizes and configurations, including, for example, LIF sockets and ZIF sockets.
LIF sockets may be suitable for detachably securing traditional electronic packages and/or IC devices with low pin counts onto a system board of an electronic system. However, ZIF sockets are more desirable for advanced electronic packages and/or IC devices which have larger pin counts, since no or zero insertion force and removal force are required. For example, advanced processor chips with high pin counts are typically installed in a ZIF socket, which is soldered directly to a system board of an electronic system. The ZIF sockets are commonly used to secure advanced processor chips onto a PCB. This is because the advanced processor chips may be accommodated without fear of damaging the chips or the electrical pins (connections) of the processor chips which provide electrical contacts from the processor chips to the system board.
A ZIF socket may typically include a release handle/lever which, when open, permits easy installation of an electronic package and/or an IC device such as a processor chip into the socket. Subsequent closure of the handle/lever may secure the processor chip in place.
However, these commonly available LIF and ZIF sockets, used for securing an electronic package and/or an IC device onto a system board of an electronic system, contain several disadvantages, especially when electrical devices such as electronic packages or IC devices are inserted in LIF or ZIF sockets that have been secured onto a PCB of an electronic system. One disadvantage that arises is related to the process of assembling a PCB. Some socket connectors are press-fit into the PCBs or a LIF socket connector is employed. These press-fit connectors are often used on double sided reflow circuit boards, which are not processed through a wave solder machine. The presence of delicate and easily bent large pin number arrays on electrical and IC devices require the devices to sit flush and squarely on the surface of socket connectors on the PCB. It follows that any planar warpage of a socket surface mount region will not mate uniformly with the planar electronic devices, and such significantly increases the probability that the pin array may not align perfectly with a pin aperture array in the surface mount region of the socket. This results in a less than perfect interconnection of the pins with the socket connector.
Socket connectors that have experienced a variety of environmental conditions such as reflow and annealing may become twisted or turned, that is warped out of shape, which exacerbates pin insertion concerns. Accordingly, there is a need to provide an apparatus and method to ensure that electrical sockets have a flat surface mount region and, where warpage has arisen, there is a need to provide both an apparatus and method to flatten the surface mount region of the socket.
The problem of socket warpage is particularly vexing in ZIF sockets of the type that include a lever or a cam to secure an electrical device to the socket, especially where the surface mount region is present on a movable portion of a socket housing.
Warpage in ZIF sockets has been identified as a concern where socket designers have sought to ensure a flat surface mount region by the inclusion of thin (e.g., sheet metal) reinforcing frames which are co-extensive with the perimeter of a top plate of the socket. The use of thin reinforcing frames requires that the top plate to be reinforced is flat when the reinforcing frames are fitted to the edges i.e., perimeter of the top plate. This less advantageous approach at best, has limited rigidity characteristics owing to the thin (sheet metal) frames, and thus does not provide for any structure to flatten a surface mount region in the event that warpage of a surface mount region arises during molding, reflow or annealing processes routinely experienced in socket manufacture and installation on a PCB.
Heretofore socket warpage has also been addressed by modifying mold flow, mold compound or redesigning the socket so that warpage is reduced. As a socket gets larger in size, this becomes harder to accomplish.